Fluid exchange devices and related systems, and methods

ABSTRACT

Devices and systems for exchanging properties between at least two fluid streams and related methods may include a valve device comprising a valve actuator configured to move at variable rates in order to selectively fill and empty at least one tank. Devices for exchanging properties between at least two fluid streams may include a valve device comprising staggered and overlapping openings positioned along a path of a valve actuator. The staggered and overlapping openings may be configured to selectively and gradually place an inlet in communication with at least one tank.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 62/758,359, filed Nov. 9, 2018, for “Fluid Exchange Devices and Related Systems, and Methods,” the disclosure of which is hereby incorporated herein in its entirety by this reference.

TECHNICAL FIELD

The present disclosure relates generally to exchange devices. More particularly, embodiments of the present disclosure relate to fluid exchange devices for one or more of exchanging properties (e.g., pressure) between fluids and systems and methods.

BACKGROUND

Industrial processes often involve hydraulic systems including pumps, valves, impellers, etc. Pumps, valves, and impellers may be used to control the flow of the fluids used in the hydraulic processes. For example, some pumps may be used to increase (e.g., boost) the pressure in the hydraulic system, other pumps may be used to move the fluids from one location to another. Some hydraulic systems include valves to control where a fluid flows. Valves may include control valves, ball valves, gate valves, globe valves, check valves, isolation valves, combinations thereof, etc.

Some industrial processes involve the use of caustic fluids, abrasive fluids, and/or acidic fluids. These types of fluids may increase the amount of wear on the components of a hydraulic system. The increased wear may result in increased maintenance and repair costs or require the early replacement of equipment. For example, abrasive, caustic, or acidic fluid may increase the wear on the internal components of a pump such as an impeller, shaft, vanes, nozzles, etc. Some pumps are rebuildable and an operation may choose to rebuild a worn pump replacing the worn parts which may result in extended periods of downtime for the worn pump resulting in either the need for redundant pumps or a drop in productivity. Other operations may replace worn pumps at a larger expense but a reduced amount of downtime.

Well completion operations in the oil and gas industry often involve hydraulic fracturing (often referred to as fracking or fracing) to increase the release of oil and gas in rock formations. Hydraulic fracturing involves pumping a fluid (e.g., frac fluid, fracking fluid, etc.) containing a combination of water, chemicals, and proppant (e.g., sand, ceramics) into a well at high pressures. The high pressures of the fluid increases crack size and crack propagation through the rock formation releasing more oil and gas, while the proppant prevents the cracks from closing once the fluid is depressurized. Fracturing operations use high-pressure pumps to increase the pressure of the fracking fluid. However, the proppant in the fracking fluid increases wear and maintenance on and substantially reduces the operation lifespan of the high-pressure pumps due to its abrasive nature.

BRIEF SUMMARY

Various embodiments may include a device for exchanging pressure between at least two fluid streams. The device may include at least one high pressure inlet, at least one low pressure inlet, at least one high pressure outlet, and at least one low pressure outlet. The at least one high pressure inlet may be configured for receiving a fluid at a first higher pressure. The at least one low pressure inlet may be configured for receiving a downhole fluid (e.g., fracking fluid, drilling fluid) at a first lower pressure. The at least one high pressure outlet may be configured for outputting the downhole fluid at a second higher pressure that is greater than the first lower pressure. The at least one low pressure outlet may be configured for outputting the fluid at a second lower pressure that is less than the first higher pressure. The device may include a valve device. The valve device may include a valve actuator configured to move at variable rates in order selectively fill and empty at least one tank in communication with the at least one low pressure outlet and the at least one high pressure inlet. The valve actuator may also be configured to selectively place the fluid at the first higher pressure in communication with the downhole fluid at the first lower pressure in order to pressurize the downhole fluid to the second higher pressure; and selectively output the fluid at the second lower pressure from the pressure exchange device through the at least one low pressure outlet.

Another embodiment may include a device for exchanging pressure between at least two fluid streams. The device may include at least one high pressure inlet, at least one low pressure inlet, at least one high pressure outlet, at least one low pressure outlet, and at least one tank. The at least one high pressure inlet may be configured for receiving a fluid at a first higher pressure. The at least one low pressure inlet may be configured for receiving a downhole fluid at a first lower pressure. The at least one high pressure outlet may be configured for outputting the downhole fluid at a second higher pressure that is greater than the first lower pressure. The at least one low pressure outlet may be configured for outputting the fluid at a second lower pressure that is less than the first higher pressure. The at least one tank may be positioned between the at least one high pressure inlet and the at least one high pressure outlet. The device may also include a valve device including a valve actuator. The valve device may include staggered and overlapping openings positioned along a path of the actuator. The staggered and overlapping openings may be configured to selectively and gradually place the at least one high pressure inlet in communication with the at least one tank.

Another embodiment may include a method of operating a device for exchanging pressure between at least two fluid streams. The method may include receiving a fluid at a first higher pressure into a high pressure inlet of the device and receiving a downhole fluid at a lower pressure into the low pressure inlet of the device. The fluid at the first higher pressure may be placed in communication with the downhole fluid at the first lower pressure by moving an actuator of the device in order to pressurize the downhole fluid to a second higher pressure that is greater than the first lower pressure. The actuator of the device may be moved at a first speed as the valve member of the actuator approaches an opening between the high pressure inlet and the low pressure inlet. A velocity of the actuator of the device may be reduced from the first speed to a second speed as the valve member of the actuator traverses the opening.

Another embodiment may include a method of operating a device for exchanging pressure between at least two fluid streams. The method may include receiving a fluid at a first higher pressure into a high pressure inlet of the device and receiving a downhole fluid at a lower pressure into the low pressure inlet of the device. The fluid at the first higher pressure may be placed in communication with the downhole fluid at the first lower pressure by moving an actuator of the device in order to pressurize the downhole fluid to a second higher pressure that is greater than the first lower pressure. The method may further include moving the actuator of the device along staggered openings between the high pressure inlet and the low pressure inlet and intersecting only a minor portion of leading ends of the staggered openings at a time as the valve member of the actuator traverses the openings.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the present disclosure, various features and advantages of embodiments of the disclosure may be more readily ascertained from the following description of example embodiments of the disclosure when read in conjunction with the accompanying drawings, in which:

FIG. 1 is schematic view of a hydraulic fracturing system according to an embodiment of the present disclosure;

FIG. 2 is cross-sectional view of a fluid exchanger device according to an embodiment of the present disclosure;

FIG. 3A is a cross-sectional view of a control valve in a first position according to an embodiment of the present disclosure;

FIG. 3B is a cross-sectional view of a control valve in a second position according to an embodiment of the present disclosure;

FIG. 4 is a cross-sectional view of a control valve according to an embodiment of the present disclosure;

FIG. 5 is a view of a valve port according to an embodiment of the present disclosure; and

FIG. 6 is a view of a valve port according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

The illustrations presented herein are not meant to be actual views of any particular fluid exchanger or component thereof, but are merely idealized representations employed to describe illustrative embodiments. The drawings are not necessarily to scale. Elements common between figures may retain the same numerical designation.

As used herein, relational terms, such as “first,” “second,” “top,” “bottom,” etc., are generally used for clarity and convenience in understanding the disclosure and accompanying drawings and do not connote or depend on any specific preference, orientation, or order, except where the context clearly indicates otherwise.

As used herein, the term “and/or” means and includes any and all combinations of one or more of the associated listed items.

As used herein, the terms “vertical” and “lateral” refer to the orientations as depicted in the figures.

As used herein, the term “substantially” or “about” in reference to a given parameter means and includes to a degree that one skilled in the art would understand that the given parameter, property, or condition is met with a small degree of variance, such as within acceptable manufacturing tolerances. For example, a parameter that is substantially met may be at least 90% met, at least 95% met, at least 99% met, or even 100% met.

As used herein, the term “fluid” may mean and include fluids of any type and composition. Fluids may take a liquid form, a gaseous form, or combinations thereof, and, in some instances, may include some solid material. In some embodiments, fluids may convert between a liquid form and a gaseous form during a cooling or heating process as described herein. In some embodiments, the term fluid includes gases, liquids, and/or pumpable mixtures of liquids and solids.

Embodiments of the present disclosure may relate to exchange devices that may be utilized to exchange one or more properties between fluids (e.g., a pressure exchanger). Such exchangers (e.g., pressure exchangers) are sometimes called “flow-work exchangers” or “isobaric devices” and are machines for exchanging pressure energy from a relatively high-pressure flowing fluid system to a relatively low-pressure flowing fluid system.

In some industrial processes, elevated pressures are required in certain parts of the operation to achieve the desired results, following which the pressurized fluid is depressurized. In other processes, some fluids used in the process are available at high-pressures and others at low-pressures, and it is desirable to exchange pressure energy between these two fluids. As a result, in some applications, great improvement in economy can be realized if pressure can be efficiently transferred between two fluids.

In some embodiments, exchangers as disclosed herein may be similar to and include the various components and configurations of the pressure exchangers disclosed in U.S. Pat. No. 5,797,429 to Shumway, issued Aug. 25, 1998, the disclosure of which is hereby incorporated herein in its entirety by this reference.

Although some embodiments of the present disclosure are depicted as being used and employed as a pressure exchanger between two or more fluids, persons of ordinary skill in the art will understand that the embodiments of the present disclosure may be employed in other implementations such as, for example, the exchange of other properties (e.g., temperature, density, etc.) and/or composition between one or more fluids and/or mixing of two or more fluids.

In some embodiments, a pressure exchanger may be used to protect moving components (e.g., pumps, valves, impellers, etc.) in processes were high pressures are needed in a fluid that has the potential to damage the moving components (e.g., abrasive fluid, caustic fluid, acidic fluid, etc.).

For example, pressure exchange devices according to embodiments of the disclosure may be implemented in hydrocarbon related processes, such as, hydraulic fracturing or other drilling operations (e.g., subterranean downhole drilling operations).

As discussed above, well completion operations in the oil and gas industry often involve hydraulic fracturing, drilling operations, or other downhole operations that use high-pressure pumps to increase the pressure of the downhole fluid (e.g., fluid that is intended to be conducted into a subterranean formation or borehole, such as, fracking fluid, drilling fluid, drilling mud). The proppants, chemicals, additives to produce mud, etc. in these fluids often increase wear and maintenance on the high-pressure pumps.

In some embodiments, a hydraulic fracturing system may include a hydraulic energy transfer system that transfers pressure between a first fluid (e.g., a clean fluid, such as a partially (e.g., majority) or substantially proppant free fluid or a pressure exchange fluid) and a second fluid (e.g., fracking fluid, such as a proppant-laden fluid, an abrasive fluid, or a dirty fluid). Such systems may at least partially (e.g., substantially, primarily, entirely) isolate the high-pressure first fluid from the second dirty fluid while still enabling the pressurizing of the second dirty fluid with the high-pressure first fluid and without having to pass the second dirty fluid directly through a pump or other pressurizing device.

While some embodiments discussed herein may be directed to fracking operations, in additional embodiments, the exchanger systems and devices disclosed herein may be utilized in other operations. For example, devices, systems, and/or method disclosed herein may be used in other downhole operations, such as, for example, downhole drilling operations.

FIG. 1 illustrates a system diagram of an embodiment of hydraulic fracturing system 100 utilizing a pressure exchanger between a first fluid stream (e.g., clean fluid stream) and a second fluid stream (e.g., a fracking fluid stream). Although not explicitly described, it should be understood that each component of the system 100 may be directly connected or coupled via a fluid conduit (e.g., pipe) to an adjacent (e.g., upstream or downstream) component. The hydraulic fracturing system 100 may include one or more devices for pressurizing the first fluid stream, such as, for example, fracking pumps 102 (e.g., reciprocating pumps, centrifugal pumps, scroll pumps, etc.). The hydraulic fracturing system 100 may include multiple fracking pumps 102, such as at least two fracking pumps 102, at least four fracking pumps 102, at least ten fracking pumps 102, at least sixteen frack pumps, or at least twenty fracking pumps 102. In some embodiments, the fracking pumps 102 may provide relatively and substantially clean fluid at a high pressure to a pressure exchanger 104 from a fluid source 101. In some embodiments, fluid may be provided separately to each fracking pump 102 (e.g., in a parallel configuration). After pressurization in the fracking pumps 102, the high pressure clean fluid 110 may be combined and transmitted to the pressure exchanger 104 (e.g., in a serial configuration).

As used herein, “clean” fluid may describe fluid that is at least partially or substantially free (e.g., substantially entirely or entirely free) of chemicals and/or proppants typically found in a fracking fluid and “dirty” fluid may describe fluid that at least partially contains chemicals and/or proppants typically found in a fracking fluid.

The pressure exchanger 104 may transmit the pressure from the high pressure clean fluid 110 to a low pressure fracking fluid (e.g., fracking fluid 112) in order to provide a high pressure fracking fluid 116. The clean fluid may be expelled from the pressure exchanger 104 as a low pressure fluid 114 after the pressure is transmitted to the low pressure fracking fluid 112. In some embodiments, the low pressure fluid 114 may be an at least partially or substantially clean fluid that substantially lacks chemicals and/or proppants aside from a small amount that may be passed to the low pressure fluid 114 from the fracking fluid 112 in the pressure exchanger 104.

In some embodiments, the pressure exchanger 104 may include one or more pressure exchanger devices (e.g., operating in parallel). In such configurations, the high pressure inputs may be separated and provided to inputs of each of the pressure exchanger devices. The outputs of each of the pressure exchanger devices may be combined as the high pressure fracking fluid exits the pressure exchanger 104. For example, and as discussed below with reference to FIG. 4, the pressure exchanger 104 may include two or more (e.g., three) pressure exchanger devices operating in parallel. As depicted, the pressure exchanger 104 may be provided on a mobile platform (e.g., a truck trailer) that may be relatively easily installed and removed from a fracking well site.

After being expelled from the pressure exchanger 104, the low pressure clean fluid 114 may travel to and be collected in a mixing chamber 106 (e.g., blender unit, mixing unit, etc.). In some embodiments, the low pressure fluid 114 may be converted (e.g., modified, transformed, etc.) to the low pressure fracking fluid 112 in the mixing chamber 106. For example, a proppant may be added to the low pressure clean fluid 114 in the mixing chamber 106 creating a low pressure fracking fluid 112. In some embodiments, the low pressure clean fluid 114 may be expelled as waste.

In many hydraulic fracturing operations, a separate process may be used to heat the fracking fluid 112 before the fracking fluid 112 is discharged downhole (e.g., to ensure proper blending of the proppants in the fracking fluid). In some embodiments, using the low pressure clean fluid 114 to produce the fracking fluid 112 may eliminate the step of heating the fracking fluid. For example, the low pressure clean fluid 114 may be at an already elevated temperature as a result of the fracking pumps 102 pressurizing the high pressure clean fluid 110. After transferring the pressure in the high pressure clean fluid 110 that has been heated by the pumps 102, the now low pressure clean fluid 114 retains at least some of that heat energy as it is passed out of the pressure exchanger 104 to the mixing chamber 106. In some embodiments, using the low pressure clean fluid 114 at an already elevated temperature to produce the fracking fluid may result in the elimination of the heating step for the fracking fluid. In other embodiments, the elevated temperature of the low pressure clean fluid 114 may result in a reduction of the amount of heating required for the fracking fluid.

After the proppant is added to the low pressure fluid 114, now fracking fluid, the low pressure fracking fluid 112 may be expelled from the mixing chamber 106. The low pressure fracking fluid 112 may then enter the pressure exchanger 104 on the fracking fluid end through a fluid conduit 108 connected (e.g., coupled) between the mixing chamber 106 and the pressure exchanger 104. Once in the pressure exchanger 104, the low pressure fracking fluid 112 may be pressurized by the transmission of pressure from the high pressure clean fluid 110 through the pressure exchanger 104. The high pressure fracking fluid 116 may then exit the pressure exchanger 104 and be transmitted downhole.

Hydraulic fracturing systems generally require high operating pressures for the high pressure fracking fluid 116. In some embodiments, the desired pressure for the high pressure fracking fluid 116 may be between about 8,000 PSI (55,158 kPa) and about 12,000 PSI (82,737 kPa), such as between about 9,000 PSI (62,052 kPa) and about 11,000 PSI (75,842 kPa), or about 10,000 PSI (68,947 kPa).

In some embodiments, the high pressure clean fluid 110 may be pressurized to a pressure at least substantially the same or slightly greater than the desired pressure for the high pressure fracking fluid 116. For example, the high pressure clean fluid 110 may be pressurized to between about 0 PSI (0 kPa) and about 1000 PSI (6,894 kPa) greater than the desired pressure for the high pressure fracking fluid 116, such as between about 200 PSI (1,379 kPa) and about 700 PSI (4,826 kPa) greater than the desired pressure, or between about 400 PSI (2,758 kPa) and about 600 PSI (4,137 kPa) greater than the desired pressure, to account for any pressure loss during the pressure and exchange process.

FIG. 2 illustrates an embodiment of a pressure exchanger 200. The pressure exchanger 200 may be a linear pressure exchanger in the sense that it is operated by moving or translating an actuation assembly substantially along a linear path. For example, the actuation assembly may be moved linearly to selectively place the low and high pressure fluids in at least partial communication (e.g., indirect communication where the pressure of the high pressure fluid may be transferred to the low pressure fluid) as discussed below in greater detail.

The linear pressure exchanger 200 may include one or more (e.g., two) chambers 202 a, 202 b (e.g., tanks, collectors, cylinders, tubes, pipes, etc.). The chambers 202 a, 202 b (e.g., parallel chambers 202 a, 202 b) may include pistons 204 a, 204 b configured to substantially maintain the high pressure clean fluid 210 and low pressure clean fluid 214 (e.g., the clean side) separate from the high pressure dirty fluid 216 and the low pressure dirty fluid 212 (e.g., the dirty side) while enabling transfer of pressure between the respective fluids 210, 212, 214, and 216. The pistons 204 a, 204 b may be sized (e.g., the outer diameter of the pistons 204 a, 204 b relative to the inner diameter of the chambers 202 a, 202 b) to enable the pistons 204 a, 204 b to travel through the chamber 202 a, 202 b while minimizing fluid flow around the pistons 204 a, 204 b.

The linear pressure exchanger 200 may include a clean control valve 206 configured to control the flow of high pressure clean fluid 210 and low pressure clean fluid 214. Each of the chambers 202 a, 202 b may include one or more dirty control valves 207 a, 207 b, 208 a, 208 b configured to control the flow of the low pressure dirty fluid 212 and the high pressure dirty fluid 216.

While the embodiment of FIG. 2 contemplates a linear pressure exchanger 200, other embodiments, may include other types of pressure exchangers that involve other mechanisms for selectively placing the low and high pressure fluids in at least partial communication (e.g., a rotary actuator such as those disclosed in U.S. Pat. No. 9,435,354, issued Sep. 6, 2016, the disclosure of which is hereby incorporated herein in its entirety by this reference, etc.).

In some embodiments, the clean control valve 206, which includes an actuation stem 203 that moves one or more stoppers 308 along (e.g., linearly along) a body 205 of the valve 206, may selectively allow (e.g., input, place, etc.) high pressure clean fluid 210 provided from a high pressure inlet port 302 to enter a first chamber 202 a on a clean side 220 a of the piston 204 a. The high pressure clean fluid 210 may act on the piston 204 a moving the piston 204 a in a direction toward the dirty side 221 a of the piston 204 a and compressing the dirty fluid in the first chamber 202 a to produce the high pressure dirty fluid 216. The high pressure dirty fluid 216 may exit the first chamber 202 a through the dirty discharge control valve 208 a (e.g., outlet valve, high pressure outlet). At substantially the same time, the low pressure dirty fluid 212 may be entering the second chamber 202 b through the dirty fill control valve 207 b (e.g., inlet valve, low pressure inlet). The low pressure dirty fluid 212 may act on the dirty side 221 b of the piston 204 b moving the piston 204 b in a direction toward the clean side 220 b of the piston 204 b in the second chamber 202 b. The low pressure clean fluid 214 may be discharged (e.g., emptied, expelled, etc.) through the clean control valve 206 as the piston 204 b moves in a direction toward the clean side 220 b of the piston 204 b reducing the space on the clean side 220 b of the piston 204 b within the second chamber 202 b. A cycle of the pressure exchanger is completed once each piston 204 a, 204 b moves the substantial length (e.g., the majority of the length) of the respective chamber 202 a, 202 b (which “cycle” may be a half cycle with the piston 204 a, 204 b moving in one direction along the length of the chamber 202 a, 202 b and a full cycle includes the piston 204 a, 204 b moving in the one direction along the length of the chamber 202 a, 202 b and then moving in the other direction to return to substantially the original position). In some embodiments, only a portion of the length may be utilized (e.g., in reduced capacity situations). Upon the completion of a cycle, the actuation stem 203 of the clean control valve 206 may change positions enabling the high pressure clean fluid 210 to enter the second chamber 202 b, thereby changing the second chamber 202 b to a high pressure chamber and changing the first chamber 202 a to a low pressure chamber and repeating the process.

In some embodiments, each chamber 202 a, 202 b may have a higher pressure on one side of the pistons 204 a, 204 b to move the piston in a direction away from the higher pressure. For example, the high pressure chamber may experience pressures between about 8,000 PSI (55,158 kPa) and about 13,000 PSI (89,632 kPa) with the highest pressures being in the high pressure clean fluid 210 to move the piston 204 a, 204 b away from the high pressure clean fluid 210 compressing and discharging the dirty fluid to produce the high pressure dirty fluid 216. The low pressure chamber 202 a, 202 b may experience much lower pressures, relatively, with the relatively higher pressures in the currently low pressure chamber 202 a, 202 b still being adequate enough in the low pressure dirty fluid 212 to move the piston 204 a, 204 b in a direction away from the low pressure dirty fluid 212 discharging the low pressure clean fluid 214. In some embodiments, the pressure of the low pressure dirty fluid 212 may be between about 100 PSI (689 kPa) and about 700 PSI (4,826 kPa), such as between about 200 PSI (1,379 kPa) and about 500 PSI (3,447 kPa), or between about 300 PSI (2,068 kPa) and about 400 PSI (2758 kPa).

Referring back to FIG. 1, in some embodiments, the system 100 may include an optional device (e.g., a pump) to pressurize the low pressure dirty fluid 212 (e.g., to a pressure level that is suitable to move the piston 204 a, 204 b toward the clean side) as it is being provided into the chambers 202 a, 202 b.

Referring again to FIG. 2, if any fluid pushes past the piston 204 a, 204 b (e.g., leak by, blow by, etc.) it will generally tend to flow from the higher pressure fluid to the lower pressure fluid. The high pressure clean fluid 210 may be maintained at the highest pressure in the system such that the high pressure clean fluid 210 may not generally become substantially contaminated. The low pressure clean fluid 214 may be maintained at the lowest pressure in the system. Therefore, it is possible that the low pressure clean fluid 214 may become contaminated by the low pressure dirty fluid 212. In some embodiments, the low pressure clean fluid 214 may be used to produce the low pressure dirty fluid 212 substantially nullifying any detriment resulting from the contamination. Likewise, any contamination of the high pressure dirty fluid 216 by the high pressure clean fluid 210 would have minimal effect on the high pressure dirty fluid 216.

In some embodiments, the dirty control valves 207 a, 207 b, 208 a, 208 b may be check valves (e.g., clack valves, non-return valves, reflux valves, retention valves, or one-way valves). For example, one or more of the dirty control valves 207 a, 207 b, 208 a, 208 b may be a ball check valve, diaphragm check valve, swing check valve, tilting disc check valve, clapper valve, stop-check valve, lift-check valve, in-line check valve, duckbill valve, etc. In additional embodiments, one or more of the dirty control valves 207 a, 207 b, 208 a, 208 b may be actuated valves (e.g., solenoid valves, pneumatic valves, hydraulic valves, electronic valves, etc.) configured to receive a signal from a controller and open or close responsive the signal.

The dirty control valves 207 a, 207 b, 208 a, 208 b may be arranged in opposing configurations such that when the chamber 202 a, 202 b is in the high pressure configuration the high pressure dirty fluid opens the dirty discharge control valve 208 a, 208 b while the pressure in the chamber 202 a, 202 b holds the dirty fill control valve 207 a, 207 b closed. For example, the dirty discharge control valve 208 a, 208 b comprises a check valve that opens in a first direction out of the chamber 202 a, 202 b, while the dirty fill control valve 207 a, 207 b comprises a check valve that opens in a second, opposing direction into the chamber 202 a, 202 b.

The dirty discharge control valves 208 a, 208 b may be connected to a downstream element (e.g., a fluid conduit, a separate or common manifold) such that the high pressure in the downstream element holds the dirty discharge valve 208 a, 208 b closed in the chamber 202 a, 202 b that is in the low pressure configuration. Such a configuration enables the low pressure dirty fluid to open the dirty fill control valve 207 a, 207 b and enter the chamber 202 a, 202 b.

FIGS. 3A and 3B illustrate a cross sectional view of an embodiment of a clean control valve 300 at two different positions. In some embodiments, the clean control valve 300 may be similar to the control valve 206 discussed above. The clean control valve 300 may be a multiport valve (e.g., 4 way valve, 5 way valve, LinX® valve, etc.). The clean control valve 300 may have one or more high pressure inlet ports (e.g., one port 302), one or more low pressure outlet ports (e.g., two ports 304 a, 304 b), and one or more chamber connection ports (e.g., two ports 306 a, 306 b). The clean control valve 300 may include at least two stoppers 308 (e.g., plugs, pistons, discs, valve members, etc.). In some embodiments, the clean control valve 300 may be a linearly actuated valve. For example, the stoppers 308 may be linearly actuated such that the stoppers 308 move along a substantially straight line (e.g., along a longitudinal axis L₃₀₀ of the clean control valve 300).

The clean control valve 300 may include an actuator 303 configured to actuate the clean control valve 300 (e.g., an actuator coupled to a valve stem 301 of the clean control valve 300). In some embodiments, the actuator 303 may be electronic (e.g., solenoid, rack and pinion, ball screw, segmented spindle, moving coil, etc.), pneumatic (e.g., tie rod cylinders, diaphragm actuators, etc.), or hydraulic. In some embodiments, the actuator 303 may enable the clean control valve 300 to move the valve stem 301 and stoppers 308 at variable rates (e.g., changing speeds, adjustable speeds, etc.).

FIG. 3A illustrates the clean control valve 300 in a first position. In the first position, the stoppers 308 may be positioned such that the high pressure clean fluid may enter the clean control valve 300 through the high pressure inlet port 302 and exit into a first chamber through the chamber connection port 306 a. In the first position, the low pressure clean fluid may travel through the clean control valve 300 between the chamber connection port 306 b and the low pressure outlet port 304 b (e.g., may exit through the low pressure outlet port 304 b).

FIG. 3B illustrates the clean control valve 300 in a second position. In the second position, the stoppers 308 may be positioned such that the high pressure clean fluid may enter the clean control valve 300 through the high pressure inlet port 302 and exit into a second chamber through the chamber connection port 306 b. The low pressure clean fluid may travel through the clean control valve 300 between the chamber connection port 306 a and the low pressure outlet port 304 a (e.g., may exit through the low pressure outlet port 304 a).

Now referring to FIGS. 2, 3A, and 3B, the clean control valve 206 is illustrated in the first position with the high pressure inlet port 302 connected to the chamber connection port 306 a providing high pressure clean fluid to the first chamber 202 a. Upon completion of the cycle, the clean control valve 206 may move the stoppers 308 to the second position thereby connecting the high pressure inlet port 302 to the second chamber 202 b through the chamber connection port 306 b.

In some embodiments, the clean control valve 206 may pass through a substantially fully closed position in the middle portion of a stroke between the first position and the second position. For example, in the first position, the stoppers 308 may maintain a fluid pathway between the high pressure inlet port 302 and the chamber connection port 306 a and a fluid pathway between the chamber connection port 306 b and the low pressure outlet port 304 b. In the second position, the stoppers 308 may maintain a fluid pathway between the high pressure inlet port 302 and the chamber connection port 306 b and a fluid pathway between the chamber connection port 306 a and the low pressure outlet port 304 a. Transitioning between the first and second positions may involve at least substantially closing both fluid pathways to change the connection of the chamber connection port 306 a from the high pressure inlet port 302 to the low pressure outlet port 304 a and to change the connection of the chamber connection port 306 b from the low pressure outlet port 304 b to the high pressure inlet port 302. The fluid pathways may at least substantially close at a middle portion of the stroke to enable the change of connections.

Opening and closing valves where fluids are operating at high pressures may result in pressure pulsations (e.g., water hammer) that can result in damage to components in the system when high pressure is suddenly introduced or removed from the system. As a result, pressure pulsations may occur in the middle portion of the stroke when the fluid pathways are closing and opening respectively.

In some embodiments, the actuator 303 may be configured to move the stoppers 308 at variable speeds along the stroke of the clean control valve 206. As the stoppers 308 move from the first position to the second position, the stoppers 308 may move at a high rate of speed while traversing a first portion of the stroke that does not involve newly introducing flow from the high pressure inlet port 302 into the chamber connection ports 306 a, 306 b. The stoppers 308 may decelerate to a low rate of speed as the stoppers 308 approach a closed position (e.g., when the stoppers 308 block the chamber connection ports 306 a, 306 b during the transition between the high pressure inlet port 302 connection and the low pressure outlet port 304 a, 304 b connection) at a middle portion of the stroke. The stoppers 308 may continue at a lower rate of speed, as the high pressure inlet port 302 is placed into communication with one of the chamber connection ports 306 a, 306 b. After, traversing the chamber connection ports 306 a, 306 b, the stoppers 308 may accelerate to another high rate of speed as the stoppers 308 approach the second position. The low rate of speed in the middle portion of the stroke may reduce the speed that the clean control valve 206 opens and closes enabling the clean control valve to gradually introduce and/or remove the high pressure from the chambers 202 a, 202 b.

In some embodiments, the motion of the pistons 204 a, 204 b may be controlled by regulating the rate of fluid flow (e.g., of the incoming fluid) and/or a pressure differential between the clean side 220 a, 220 b of the pistons 204 a, 204 b, and the dirty side 221 a, 221 b of the pistons 204 a, 204 b at least partially with the movement of the clean control valve 206. In some embodiments, it may be desirable for the piston 204 a, 204 b in the low pressure chamber 202 a, 202 b to move at substantially the same speed as the piston 204 a, 204 b in the high pressure chamber 202 a, 202 b either by manipulating their pressure differentials in each chamber and/or by controlling the flow rates of the fluid in and out of the chambers 202 a, 202 b. However, the piston 204 a, 204 b in the low pressure chamber 202 a, 202 b may tend to move at a greater speed than the piston 204 a, 204 b in the high pressure chamber 202 a, 202 b.

In some embodiments, the rate of fluid flow and/or the pressure differential may be varied to control acceleration and deceleration of the pistons 204 a, 204 b (e.g., by manipulating and/or varying the stroke of the clean control valve 206 and/or by manipulating the pressure in the fluid streams with one or more pumps). For example, increasing the flow rate and/or the pressure of the high pressure clean fluid 210 when the piston 204 a, 204 b is near a clean end 224 of the chamber 202 a, 202 b at the beginning of the high pressure stroke may increase the rate of fluid flow and/or the pressure differential in the chamber 202 a, 202 b. Increasing the rate of fluid flow and/or the pressure differential may cause the piston 204 a, 204 b to accelerate to or move at a faster rate. In another example, the flow rate and/or the pressure of the high pressure clean fluid 210 may be decreased when the piston 204 a, 204 b approaches a dirty end 226 of the chamber 202 a, 202 b at the end of the high pressure stroke. Decreasing the rate of fluid flow and/or the pressure differential may cause the piston 204 a, 204 b to decelerate and/or stop before reaching the dirty end of the respective chamber 202 a, 202 b.

Similar control with the stroke of the clean control valve 206 may be utilized to prevent the piston 204 a, 204 b from traveling to the furthest extent of the clean end of the chambers 202 a, 202 b. For example, the clean control valve 206 may close off one of the chamber connection ports 306 a, 306 b before the piston 204 a, 204 b contacts the furthest extent of the clean end of the chambers 202 a, 202 b by preventing any further fluid flow and slowing and/or stopping the piston 204 a, 204 b. In some embodiments, the clean control valve 206 may open one the chamber connection ports 306 a, 306 b into communication with the high pressure inlet port 302 before the piston 204 a, 204 b contacts the furthest extent of the clean end of the chambers 202 a, 202 b in order to slow, stop, and/or reverse the motion of the piston 204 a, 204 b.

If the pistons 204 a, 204 b reach the clean end 224 or dirty end 226 of the respective chambers 202 a, 202 b the higher pressure fluid may bypass the piston 204 a, 204 b and mix with the lower pressure fluid. In some embodiments, mixing the fluids may be desirable. For example, if the pistons 204 a, 204 b reach the dirty end 226 of the respective chambers 202 a, 202 b during the high pressure stroke, the high pressure clean fluid 210 may bypass the piston 204 a, 204 b (e.g., by traveling around the piston 204 a, 204 b or through a valve in the piston 204 a, 204 b) flushing any residual contaminants from the surfaces of the piston 204 a, 204 b. In some embodiments, mixing the fluids may be undesirable. For example, if the pistons 204 a, 204 b reach the clean end 224 of the respective chambers 202 a, 202 b during the low pressure stroke, the low pressure dirty fluid 212 may bypass the piston 204 a, 204 b and mix with the low pressure clean fluid contaminating the clean area in the clean control valve 206 with the dirty fluid.

In some embodiments, the system 100 may prevent the pistons 204 a, 204 b from reaching the clean end 224 of the respective chambers 202 a, 202 b. For example, the clean control valve 206 may include a control device (e.g., sensor, safety, switch, etc.) to trigger the change in position of the clean control valve 206 on detecting the approach of the piston 204 a, 204 b to the clean end 224 of the respective chamber 202 a, 202 b such that the system 100 may utilize the clean control valve 206 to change flow path positions before the piston 204 a, 204 b reaches the clean end 224 of the chamber 202 a, 202 b.

In some embodiments, pressure spikes may occur in the fluids. For example, pressure spikes may occur in the high pressure clean fluid 210 when the clean control valve 206 closes or opens. In some embodiments, the chambers 202 a, 202 b and pistons 204 a, 204 b may dampen (e.g., reduce, balance, etc.) any pressure spikes in the high pressure clean fluid 210 when transferring pressure from the high pressure clean fluid 210 to the dirty fluid 212 producing the high pressure dirty fluid 216 while minimizing pressure spikes.

In some embodiments, duration of each cycle may correlate to the production of the system 100. For example, in each cycle the pressure exchanger 200 may move a specific amount of dirty fluid defined by the combined capacity of the chambers 202 a, 202 b. In some embodiments, the pressure exchanger 200 may move between about 40 gallons (75.7 liters) and about 90 gallons (340.7 liters), such as between about 60 gallons (227.1 liters) and about 80 gallons (302.8 liters), or between about 65 gallons (246.1 liters) and about 75 gallons (283.9 liters). For example, in a system with one or more tanks (e.g., two tanks), each tank in the pressure exchanger 200 may move between about 40 gallons (75.7 liters) and about 90 gallons (340.7 liters) (e.g., two about 60 gallon (227.1 liters) tanks that move about 120 gallons (454.2 liters) per cycle).

In some embodiments, the duration of the cycles may be controlled by varying the rate of fluid flow and/or pressure differential across the pistons 204 a, 204 b with the clean control valve 206. For example, the flow rate and/or pressure of the high pressure clean fluid 210 may be controlled such that the cycles correspond to a desired flow rate of the dirty fluid 212. In some embodiments, the flow rate and/or the pressure may be controlled by controlling a speed of the frac pumps 102 (FIG. 1) (e.g., through a variable frequency drive (VFD), throttle control, etc.), through a mechanical pressure control (e.g., variable vanes, pressure relief system, bleed valve, etc.), or by changing the position of the clean control valve 206 to restrict flow into or out of the chambers 202 a, 202 b.

In some embodiments, maximum production may be the desired condition which may use the shortest possible duration of the cycle. In some embodiments, the shortest duration of the cycle may be defined by the speed of the actuator 303 on the clean control valve 206, 300. In some embodiments, the shortest duration of the cycle may be defined by the maximum pressure of the high pressure clean fluid 210. In some embodiments, the shortest duration may be defined by the response time of the clean control valve 206, 300.

In some embodiments, a pressure difference between the high pressure clean fluid 210 and the low pressure clean fluid 214 may require small incremental movement as the clean control valve 206 opens and closes. For example, if the pressure difference between the high pressure clean fluid 210 and the low pressure clean fluid 214 is high even a small opening could allow for large pressure pulsations and/or fast pressure increases on the low pressure side of the clean control valve 206. For accurate pressure control across a valve, the valve may utilize flow restriction to maintain a pressure differential across the valve. Systems with high pressure differences may make it difficult to create enough flow restriction to control the pressure in the chambers 202 a, 202 b with the clean control valve 206.

FIG. 4 illustrates a cross-sectional view of an embodiment of a clean control valve 400. In some embodiments, the clean control valve 400 may be similar to the control valves 206 and 300 discussed above. The clean control valve 400 may have one or more inlet ports (e.g., high pressure inlet ports 402), one or more outlet ports (e.g., low pressure outlet ports 404 a, 404 b), and one or more outlet and/or inlet ports (e.g., chamber connection ports 406 a, 406 b). The clean control valve 400 may include one or more stoppers 408 on a valve stem 401. In some embodiments, the clean control valve 400 may be a linearly actuated valve. For example, the stoppers 408 may be linearly actuated such that the stoppers 408 move along a substantially straight line (e.g., with the valve stem 401 along a longitudinal axis L₄₀₀ of the clean control valve 400). In some embodiments, the clean control valve 400 may be cylindrical (e.g., with a substantially circular cross-section, with an annular shaped cross-section, etc.) or may be another cross-sectional shape (e.g. a polygonal shape, rectangular shape, etc.).

In some embodiments, at least one of the low pressure outlet ports 404 a, 404 b, the high pressure inlet ports 402, and the chamber connection ports 406 a, 406 b may include one or more openings 410. For example, the chamber connection ports 406 a, 406 b may include at least three openings 410 or at least four openings 410 and/or the low pressure outlet ports 404 a, 404 b may include at least three openings 410 or at least four openings 410. In some embodiments, the openings 410 may be defined by a valve body liner 412 (e.g., a housing, a sleeve, which may be replaceable). In some embodiments, the body liner 412 may comprise a metal material (e.g., stainless steel, a polymer material, or combinations thereof). The valve body liner 412 may include opening walls 414 that may define the openings 410. In some embodiments, the openings 410 may be defined such that a larger (e.g., major) dimension of the openings 410 is perpendicular to the longitudinal axis L₄₀₀ of the clean control valve 400 and the path of the stoppers 408. For example, a major dimension of the openings 410 extends along a lateral dimension (e.g., along a circumference) of the control valve 400. In additional embodiments, a major dimension of the openings 410 extends along the longitudinal axis L₄₀₀ of the clean control valve 400.

In some embodiments, the openings 410 may be defined in substantially uniform shapes such as, square or rectangular openings. However, substantially uniform shapes may result in an abrupt increase or decrease in open area when the stoppers 408 initially open or finish closing the ports. In some embodiments, the openings 410 may be defined in shapes of gradually increasing or decreasing area, for example, triangular shapes, elliptical shapes, oval shaped, circular shapes, parabolic shapes, polygonal shapes, etc.) such that as the stoppers 408 move across the openings 410, the area of the opening 410 that enables fluid flow may decrease or increase more gradually as compared to a substantially uniform opening.

In some embodiments, the openings 410 may be arranged such that, as the stoppers 408 move along the substantially straight line, each opening 410 is opened and/or closed individually at a different time (e.g., separately). For example, as the stoppers 408 move from a first position to a second position, the stoppers 408 may close (e.g., block, obstruct, etc.) a first opening 410 in each of the chamber connection ports 406 a, 406 b. The stoppers 408 may then close a second opening 410 in each of the chamber connection ports 406 a, 406 b. The stoppers 408 may then continue to close additional openings 410 in each of the chamber connection ports 406 a until all of the openings 410 in each of the chamber connection ports 406 a, 406 b are closed. The stoppers 408 may continue to move along the substantially straight line opening the first opening 410 in each of the chamber connection ports 406 a, 406 b. The stoppers 408 may then open the second opening 410 in each of the chamber connection ports 406 a, 406 b. The stoppers 408 may then continue to open any additional openings 410 in each of the chamber connection ports in order until all of the openings 410 in each of the chamber connection ports is open.

FIG. 5 illustrates an embodiment of a port 500 of a valve device (e.g., clean control valve 206, 300 (FIGS. 2, 3A, and 3B)), with multiple openings 510. Referring to FIGS. 4 and 5, the openings 510 may have a long dimension 502 and a short dimension 504 (e.g., based on the total number of openings 510 and/or desired opening/pressure/flow characteristics). For example, the openings 510 (e.g., high pressure openings) may be 4.25 inches (10.795 cm) long and 0.50 inches (1.27 cm) wide and another set of openings 510 (e.g., low pressure openings) may be 3.00 inches (7.62 cm) long and 0.50 inches (1.27 cm) wide. The openings 510 may be arranged such that the long dimension 502 is substantially perpendicular to the path of the stoppers 408 (FIG. 4), such that the openings 510 and the port 500 operate similar to the low pressure outlet ports 404 a, 404 b and/or the chamber connection ports 406 a, 406 b as described above and illustrated in FIG. 4.

In some embodiments, the openings 510 may be arranged such that the long dimension 502 is substantially parallel with the path of the stoppers 408 and an end 506 of each opening 510 may be substantially aligned (e.g., axially aligned). For example, the stoppers 408 may begin to expose an area (e.g., a rounded end) of each opening 510 (e.g., intersect each opening) at substantially the same time as the stoppers 408 begin to move across the openings from a substantially closed (e.g., blocked, obstructed) position. The exposed area of the openings 510 may gradually increase as the stoppers 408 move across the openings 510.

In some embodiments, a speed of the stoppers 408 may be varied to provide a controlled increase in flow through the openings 510. For example, when there is a large pressure difference across the openings, the pressure may rapidly rise on the lower pressure side of the openings 510 when the openings 510 begin to open exposing a small area (e.g., cross-sectional area) of the opening 510. The speed of the actuator 303 (FIG. 3) may be varied to control a rate of the pressure increase on the low pressure side of the stoppers 408. For example, the stoppers 408 may move slowly when initially exposing the openings 510, thereby, restricting flow of a fluid through the openings 510 and reducing the rate of the pressure increase. As more of the area of the openings 510 is exposed, the stoppers 408 may move at a faster speed. The faster speed may be utilized to enable the pressures on either side of the openings 510 to equalize or may be implemented once the pressures on either side of the openings 510 have already been equalized.

When the stoppers 408 close the openings 510, the speed of the stoppers 408 may vary. For example, as the stoppers 408 begin reducing the exposed area of the openings 510, the stoppers may move at a higher rate of speed. As the exposed area of the openings 510 decreases to a small exposed area, the stoppers 408 may reduce speed to avoid abruptly interrupting a flow of the fluid through the openings 510.

FIG. 6 illustrates an embodiment of a port 600 of a valve device (e.g., clean control valve 206, 300 (FIGS. 2, 3A, and 3B)), with multiple openings 610, which may be similar to and utilized in the same or similar manner as the openings 410, 510 discussed herein with reference to FIGS. 4 and 5.

Referring to FIGS. 4 and 6, the openings 610 may have a long dimension 602 and a short dimension 604. The openings 610 may be arranged such that the long dimension 602 is substantially parallel with the path of the stoppers 408 and an end 606 (e.g., leading end) of each of the openings 610 is not substantially aligned with the end 606 of the other openings 610 (e.g., aligned along a direction transverse to the longitudinal axis L₄₀₀ (FIG. 4). For example, a second opening 610 b may be arranged adjacent (e.g., in a direction perpendicular to the long dimension 602 of the openings 610) a first opening 610 a. As depicted, the second opening 610 b may be offset in a direction of the path of the stoppers 408 (e.g., offset in a direction substantially parallel with the longitudinal axis L₄₀₀ of the clean control valve 400 (FIG. 4), or axially offset) such that when the stoppers 408 begin to move across the openings from a substantially closed position, the stoppers 408 may begin to expose an area of the first opening 610 a while the area of the second opening 610 b remains closed (e.g., blocked by the stoppers 408).

In some embodiments, the offset between the first opening 610 a and the second opening 610 b may less than about 50% of the long dimension 602 of the openings, such as between about 5% or 10% of the long dimension and about 40% of the long dimension, or about the short dimension 604.

As further depicted, a third opening 610 c may be offset from the second opening 610 b (e.g., in additional to being offset from the first opening 610 a). For example, the third opening 610 c may be offset from the second opening 610 b by substantially the same amount as the second opening 610 b is offset from the first opening 610 a. In some embodiments, the offset between the third opening 610 c and the second opening 610 b may be a different offset (e.g., smaller offset or larger offset) than the offset between the first opening 610 a and the second opening 610 b.

In some embodiments, the gradual or staggered offsets of each opening 610 may allow for a greater flow restriction when the port 600 initially opens, with the stoppers 408 beginning to move and initially only exposing a small portion of the area of the first opening 610 a. As the stoppers 408 continue to move, the exposed area of the first opening 610 a may continue to increase until the stoppers 408 reach the end 606 (e.g., a leading end) of the second opening 610 b (e.g., intersect the end 606 of the second opening 610 b). As the stoppers 408 continue to move, an area of the second opening 610 b may begin to be exposed as the exposed area of the first opening 610 a continues to expand. Both the exposed areas of the first and second openings 610 a, 610 b may continue to expand until the stoppers 408 reach the end 606 of the second opening 610 b. As the stoppers 408 continue to move, an area of the third opening 610 c may begin to be exposed as the exposed areas of the first and second openings 610 a, 610 b continue to expand. The exposed areas of the first, second, and third openings 610 a, 610 b, 610 c may continue to expand until the stoppers 408 reach the opposite end 607 of the first opening 610 a (e.g., intersect the opposite end 607 of the first opening 610 a). The entire area of the first opening 610 a may be exposed and the stoppers 408 may continue to move with the exposed areas of the second and third opening 610 b, 610 c continuing to grow until the stoppers 408 reach the opposite end 607 of the second opening 610 b. The entire areas of the first and second openings 610 a, 610 b may be exposed and the stoppers 408 may continue to move with the exposed area of the third opening 610 c continuing to grow until the stoppers 408 reach the opposite end 607 of the third opening 610 c. Once the areas of all of the openings 610 are exposed the port 600 may be fully open.

The port 600 may operate in a similar, reverse manner when the stoppers 408 move in an opposite direction beginning with the port 600 fully open and the areas of all of the openings 610 exposed, and finishing with the port 600 substantially closed and each of the openings 610 substantially closed (e.g., blocked or obstructed by the stoppers 408 (FIG. 4)).

In some embodiments, the staggering of the openings 610 may enable the stoppers 408 to traverse the openings at greater speed as the staggered openings 610 will open one at a time, thereby, reducing the amount of high pressure fluid that is enabled to pass through the openings 610. Moving the stoppers 408 at greater speeds may enable faster cycles of the valve. In some embodiments, the greater speeds may reduce the amount of fluid jetting and/or cavitation that occurs when the exposed area of the opening 610 is relatively smaller as the time period with such a small exposed area is reduced with the faster moving stoppers 408.

In some embodiments, the openings 610 may be staggered along the outer circumference where two or more openings 610 may have aligned leading ends while still being offset form the leading ends of the remaining openings 610.

In some embodiments, the stoppers 408 may be controlled with a varying speed to regulate the flow through the openings 610. For example, the stoppers 408 may move at a slower rate when the stoppers 408 are only interacting with one opening 610, and at a faster rate when the stoppers 408 are interacting with two openings 610, and at an even faster rate when the stoppers 408 are interacting with three openings 610, etc. As the stoppers 408 interact with more openings, the pressure differential across the port 600 may decrease and a flow coefficient (e.g., flow capacity (Cv), etc.) may increase as the exposed areas of the openings 410 increase.

In some embodiments, the stoppers 408 may be controlled with a varying speed such that the increase in the flow coefficient may be substantially constant (e.g., approaching linear) with respect to time. For example, the stoppers 408 may initially move at a high rate of speed, may transition to a lower rate of speed when encountering one or more of the openings 610, and then may increase back to a higher rate of speed after flow through the openings 610 has stabilized. In some embodiments, the stoppers 408 may initially move at a high rate of speed when only traversing the first opening 610 a. The speed of the stoppers 408 may decrease as the stoppers 408 begin to traverse the second opening 610 b to compensate for the increase in flow coefficient that may result from the added area of the second opening 610 b. The speed of the stoppers 408 may further decrease as the stoppers 408 begin to traverse the third opening 610 c to compensate for the increase in the flow coefficient that may result from the added area of the third opening 610 c. The speed of the stoppers 408 may remain constant as the stoppers 408 begin to traverse the third opening 610 c. For example, the increases in the flow coefficients of the first opening 610 a and/or the second opening 610 b may begin to decrease such that the change in the combined flow coefficient of the port 600 may continue to increase at a substantially constant rate as the third opening 610 c begins to open. As the stoppers 408 continue to traverse the openings 610, the increases in the flow coefficient may decrease until the flow coefficient is substantially constant as the openings 610 approach a fully open position (e.g., substantially open, at least partially open, etc.). As the increases in the flow coefficient decrease the speed of the stoppers 408 may increase to maintain a substantially constant increase in the flow coefficient with respect to time.

In some embodiments, the variable speed of the stoppers 408 may provide for greater control of the flow coefficient of the port 500 by traveling at reduced speed when the exposed area of the openings is relatively small. As the exposed area of the opening 510 increases, the rate of change in the flow capacity rating (e.g., the flow coefficient) may begin to decrease. As the exposed area of the opening 510 approaches a maximum area (e.g., substantially fully open), the flow coefficient may remain substantially constant (e.g., plateau, reach steady-state). The speed of the stoppers 408 may increase as the rate of change in the flow coefficient decreases such that the flow coefficient may change at a substantially constant rate (e.g., approaching linear with respect to time).

In some embodiments, in addition to or alternative from the staggering of the openings 410, 510, 610, one or more of the stoppers 408 may be shaped to gradually expose the openings 410, 510, 610 to fluid flow. For example, an end of the plug may comprise an offset or rounded surface (e.g., slanted, arcuate, scalloped, rounded, circuitous, tortuous, transverse surfaces) that will gradually expose the openings 410, 510, 610.

As discussed above, opening and closing valves where fluids are operating at high pressures may result in pressure pulsations (e.g., water hammer) that can result in damage to components in the system when high pressure is suddenly introduced or removed from the system. Further, high pressure differentials across the valve port 500 may cause fluid jetting and/or cavitation (e.g., sudden vaporization) when the exposed area of the openings 510 is relatively small. If the stoppers 408 move at a reduced speed when the exposed area of the openings 510 is small (e.g., at initial opening or final closing), it may result in fluid jetting and/or cavitation for longer periods of time which may result in damage to internal components of the system. However, by varying the speed of the stoppers 408 and/or varying the geometry (e.g., spacing) of the openings 510 in accordance with embodiments of the instant disclosure, may enable the reduction of fluid jetting, cavitation, and pressure pulsations during the opening and/or closing of the valve assembly.

Now referring to FIGS. 1 and 2. In some embodiments, the pressure exchanger 104 may be formed from multiple linear pressure exchangers 200 operating in parallel. For example the pressure exchanger 104 may be formed from two or more pressure exchangers (e.g., three, four, five, or more pressure exchangers stacked in a parallel configuration. In some embodiments, the pressure exchanger 104 may be modular such that the number of linear pressure exchangers 200 may be changed by adding or removing sections of linear pressure exchangers based on flow requirements. In some embodiments, an operation may include multiple systems operating in an area and the pressure exchangers 104 for each respective system may be adjusted as needed by adding or removing linear pressure exchangers from other systems in the same area.

Embodiments of the instant disclosure may provide systems including pressure exchangers that may act to reduce the amount of wear experienced by high pressure pumps, turbines, and valves in systems with abrasive, caustic, or acidic fluids. The reduced wear may enable the systems to operate for longer periods with less down time and costs associated with repair and/or replacement of components of the system resulting in increased revenue or productivity for the systems. In operations such as fracking operations, where abrasive fluids are used at high temperatures, repairs, replacement, and downtime of components of the system can result in millions of dollars of losses in a single operation. Embodiments of the present disclosure may result in a reduction in wear experienced by the components of systems where abrasive, caustic, or acidic fluids are used at high temperatures. The reduction in wear will generally result in cost reduction and increased revenue production.

In some embodiments, increasing flow restriction across openings in a valve handling a fluid a relatively high pressure may result in relatively improved control of the flow properties (e.g., pressure, flow rate, etc.). Embodiments of the present disclosure may enable a valve to take advantage of flow restrictions through the opening in the valve, by varying the speed of an actuator in the valve and/or by openings configured to provide a gradual introduction of high pressure fluid through the openings, which may reduce abrupt pressurization and jetting fluid velocities that cause cavitation and fluid jetting erosion, thereby reducing wear on components.

While the present disclosure has been described herein with respect to certain illustrated embodiments, those of ordinary skill in the art will recognize and appreciate that it is not so limited. Rather, many additions, deletions, and modifications to the illustrated embodiments may be made without departing from the scope of the disclosure as hereinafter claimed, including legal equivalents thereof. In addition, features from one embodiment may be combined with features of another embodiment while still being encompassed within the scope of the disclosure as contemplated by the inventors. 

What is claimed is:
 1. A device for exchanging pressure between at least two fluid streams, the device comprising: at least one high pressure inlet for receiving a first fluid at a first higher pressure; at least one low pressure inlet for receiving a second fluid at a first lower pressure; at least one high pressure outlet for outputting the second fluid at a second higher pressure that is greater than the first lower pressure; at least one low pressure outlet for outputting the first fluid at a second lower pressure that is less than the first higher pressure; at least one tank positioned between the at least one high pressure inlet and the at least one high pressure outlet; and a valve device comprising a valve actuator, the valve device comprising staggered and overlapping openings positioned along a path of one or more valve members coupled to the valve actuator, the staggered and overlapping openings configured to selectively and gradually place the at least one high pressure inlet in communication with the at least one tank, wherein the valve device is configured to: move the valve actuator at a first speed as the one or more valve members approach one opening of the staggered and overlapping openings between the at least one high pressure inlet and the at least one low pressure inlet; and reduce a velocity of the valve actuator from the first speed to a second, lower speed as the one or more valve members traverse the opening.
 2. The device of claim 1, wherein the at least one tank is positioned between the at least one low pressure inlet and the at least one low pressure outlet.
 3. The device of claim 1, wherein the valve device is configured to transmit the first fluid at the first higher pressure through the staggered and overlapping openings into the at least one tank and to transmit the first fluid at the second lower pressure through the staggered and overlapping openings out of the at least one tank.
 4. The device of claim 1, wherein the valve device is configured to selectively at least partially fill and at least partially empty the at least one tank comprising at least two tanks, each tank being in communication with the at least one high pressure inlet comprising a single inlet and one respective outlet of the at least one low pressure outlet comprising at least two low pressure outlets.
 5. The device of claim 1, wherein the valve device is configured to: selectively place the first fluid at the first higher pressure in communication with the second fluid at the first lower pressure in order to pressurize the second fluid to the second higher pressure; and selectively output the first fluid at the second lower pressure from the device through the at least one low pressure outlet.
 6. The device of claim 1, wherein the valve actuator is configured to move at variable rates in order selectively fill and empty the at least one tank.
 7. The device of claim 1, wherein the valve actuator is a linear valve actuator configured to move the one or more valve members along a linear path.
 8. The device of claim 7, wherein the staggered and overlapping openings are staggered along the linear path of the linear valve actuator.
 9. The device of claim 1, wherein a leading end of each of the staggered and overlapping openings are positioned such that, when the one or more valve members travel along the path of the one or more valve members, a leading side of the one or more valve members only crosses a portion of one or more of the leading ends of the staggered and overlapping openings at a time.
 10. The device of claim 1, wherein a leading end of each of the staggered and overlapping openings are axially offset along an annular shaped housing of the valve device through which the path of the one or more valve members is defined.
 11. The device of claim 1, wherein the at least one high pressure inlet is configured to receive the first fluid comprising a clean fluid, and wherein the at least one low pressure inlet is configured to receive the second fluid comprising a downhole fluid.
 12. A device for exchanging at least one property between at least two fluid streams, the device comprising: at least one high pressure inlet for receiving a fluid at a first higher pressure; at least one low pressure inlet for receiving a downhole fluid at a first lower pressure; at least one high pressure outlet for outputting the downhole fluid at a second higher pressure that is greater than the first lower pressure; at least one low pressure outlet for outputting the fluid at a second lower pressure that is less than the first higher pressure; a valve device comprising a valve actuator configured to move one or more valve members in order selectively fill and empty at least one tank in communication with the at least one low pressure outlet and the at least one high pressure inlet, wherein the valve device comprises openings configured to selectively place the at least one high pressure inlet in communication with the at least one tank, and wherein the openings are staggered along a linear path of the one or more valve members, each of the openings overlapping with at least one adjacent opening of the openings in a direction transverse to the linear path of the one or more valve members, the openings for fluid communication with the at least one tank extending through only one lateral side of the valve device, the valve device configured to: selectively place the fluid at the first higher pressure in communication with the downhole fluid at the first lower pressure in order to pressurize the downhole fluid to the second higher pressure; and selectively output the fluid at the second lower pressure through the at least one low pressure outlet.
 13. The device of claim 12, wherein a leading end of each opening of the openings is offset from a leading end of an adjacent opening of the openings along the linear path of the one or more valve members.
 14. The device of claim 12, wherein the valve device is configured to gradually increase and gradually decrease flow of the fluid at the first higher pressure through the openings as the one or more valve members travel from a leading end of each of the openings to a trailing end of each of the openings.
 15. The device of claim 13, wherein the openings of the valve device are positioned such that the one or more valve members initially pass the leading end of only one of the openings.
 16. The device of claim 12, wherein a long dimension of at least one of the openings is aligned along the linear path of the one or more valve members and a short dimension of the at least one of the openings is aligned along a direction transverse to the linear path of the one or more valve members.
 17. The device of claim 12, wherein a leading end of each of the openings is axially offset from each leading end of adjacent openings of the openings along the linear path of the one or more valve members.
 18. A method of operating a device for exchanging pressure between at least two fluid streams, the method comprising: receiving a fluid at a first higher pressure into a high pressure inlet of the device; receiving a downhole fluid at a first lower pressure into a low pressure inlet of the device; placing the fluid at the first higher pressure in communication with the downhole fluid at the first lower pressure by moving an actuator of the device in order to pressurize the downhole fluid to a second higher pressure that is greater than the first lower pressure; moving the actuator of the device at a first speed as a valve member of the actuator approaches an opening between the high pressure inlet and the low pressure inlet; reducing a velocity of the actuator of the device from the first speed to a second, lower speed as the valve member of the actuator traverses the opening, wherein the opening comprises staggered openings; and intersecting only a minor portion of leading ends of the staggered openings at a time as the valve member of the actuator traverses the staggered openings.
 19. A method of operating a device for exchanging pressure between at least two fluid streams, the method comprising: receiving a fluid at a first higher pressure into a high pressure inlet of the device; receiving a downhole fluid at a first lower pressure into a low pressure inlet of the device; placing the fluid at the first higher pressure in communication with the downhole fluid at the first lower pressure by moving an actuator of the device in order to pressurize the downhole fluid to a second higher pressure that is greater than the first lower pressure; moving one or more valve members of the device along staggered openings between the high pressure inlet and the low pressure inlet, the staggered openings being positioned on one side of the device in communication with one or more pressure-exchanging volumes along a path of the one or more valve members; and intersecting only a minor portion of leading ends of the staggered openings as the one or more valve members traverse the staggered openings; and gradually increasing an area of the staggered openings through which the fluid is flowing as the one or more valve members move from the leading ends of the staggered openings toward trailing ends of the staggered opening.
 20. The method of claim 19, further comprising gradually decreasing the area of the staggered openings through which the fluid is flowing as the one or more valve members approach the trailing ends of the staggered opening.
 21. The method of claim 19, further comprising initially passing the leading end of only one of the staggered openings with the one or more valve members. 